textproduct: Rapid City

KEY MESSAGES

- Very hot temperatures will continue through the week, with record high temperatures possible and dangerous heat.

- Critical to near-critical fire weather conditions will continue.

UPDATE

Issued at 913 PM MDT Mon Jul 13 2026

00z KUNR sounding tells the story again this evening. Hot. 03z surface analysis has high over IA with weak frontal boundary from eastern MT into eastern UT. Water vapour loop had strong upper ridge across the northern Plains into the upper Midwest. Plenty of stars to be seen with very clear skies tonight.

Current forecast in good shape. Strong upper/thermal ridge will move little through Wednesday, but then the upper ridge will weaken, especially in the west where disturbances start to impinge on the western edge of the CWA allowing monsoonal moisture to sneak in. Result will be continued hot weather and a slow increase in PoPs by the end of the week/weekend. However, confidence in PoPs is low given convective nature as well as ensemble spreads for moisture availability later in the period. Temperature spreads are tight. Heat headlines on target.

DISCUSSION

(This Evening Through Monday) Issued at 212 PM MDT Mon Jul 13 2026

Water vapor imagery shows moisture circulating around upper level high pressure centered over the Central Plains. At the surface, high pressure is centered over Alberta and Saskatchewan with another area of high pressure over the middle Mississippi River Valley. A stationary boundary extends between the two areas of high pressure from western Ontario into northwest Wyoming. At 19Z, temperatures are hot, with most sites in the 90s and a few sites already above 100 degrees. Winds are mostly south to southeast at speeds of 10 to 25 mph, with gusts around 35 mph.

The strong upper level thermal ridge remains in place today and Tuesday before it starts to shift east and weaken on Wednesday, and more-so by the weekend. Widespread high temperatures in the 100-107 degree range will continue on Tuesday, with temperatures expected to cool a degree or two each day, Wednesday through the weekend. Winds will remain gusty from the south and south east through Wednesday, due to the tightened pressure gradient.

As the ridge begins to break down Wednesday, a surface low will develop over eastern Montana and western North Dakota. A trough extending from the surface low will drift through the forecast area Wednesday night. With dry air in place, the only impact from this will be a shift in the winds from the north and northwest.

Monsoonal moisture begins to stream into the Desert Southwest and Intermountain West this week. Models indicate some additional moisture may make its way into the forecast area by late week, although anomalously high 500mb heights continue. This will lead to the possibility of an afternoon or evening thunderstorm Thursday, with slightly higher probabilities Friday through Sunday.

AVIATION

(For the 06Z TAFS Through 06Z Tuesday Night) Issued At 913 PM MDT Mon Jul 13 2026

Expect VFR conditions through the forecast period. Gusty south/southeast winds will persist through Tuesday, especially on the western SD plains Tuesday afternoon.

FIRE WEATHER

Issued At 913 PM MDT Mon Jul 13 2026

Dry, hot and breezy conditions will continue through mid-week, leading to critical fire weather conditions from the northeastern Wyoming to the far western South Dakota plains. On Tuesday, breezy south to southeast winds with gusts up to 35 mph will combine with the very low humidity of 15% or less. This will continue to support critical fire weather conditions. In addition, poor humidity recoveries are expected each night. A Red Flag Warning continues until Tuesday evening. The strong upper level ridge begins to break down on Wednesday, however, critical or near-critical fire weather conditions may still be possible. Therefore, we will continue to monitor the potential for critical conditions for the second half of the week. If monsoon moisture is available for the end of the week, dry lightning may become a concern depending on low level moisture availability.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory until 9 PM MDT /10 PM CDT/ Thursday for SDZ001-002- 012>014-025>027-030>032-041>044-046-047-049-072>078. Red Flag Warning until 9 PM MDT Tuesday for SDZ322>332. WY...Heat Advisory until 9 PM MDT Thursday for WYZ054>056-058>060.